Technical Field
The present invention relates to a structure of a motor capable of enhancing sensing efficiency and structural reliability.
Discussion of Related Art
Generally, an electronic power steering system (EPS) is used to ensure steering stability of vehicles. The EPS enables a driver to drive safely by ensuring a cornering stability and providing quick restoring force of the steering since an electronic control unit drives a motor according to driving conditions sensed from a vehicle speed sensor, torque angle sensor, torque sensor, and the like. The EPS enables the driver to perform a steering work with less power as the motor assists the torque of a steering wheel that the driver operates, for which a brushless direct current motor (BLCD motor) is used. Major portion of the BLCD motor is formed by a stator and a rotor, in which a rotator wound by a coil and a stator coupled with a magnet interact with each other electromagnetically to rotate the rotor.
The EPS motor is controlled by exchanging information through a signal (hall device) with a sensing magnet. Generally, a sensing plate assembly made by a bonding coupling of a plate with a magnet using an adhesive is coupled to a rotating shaft for the sensing magnet to be coupled with the rotor, to maintain a pole pitch with a drive magnet, and to maintain a gap with a hall sensor. However, such a coupling structure of coupling the sensing magnet with the sensing plate using the adhesive may cause a trouble in drive due to a phenomenon such as separation between the magnet and the plate or separation between the sensing plate and the rotating shaft by a temperature environment, a mechanical stress deviation, an external force, or the like.